Semiconductor laser device

ABSTRACT

This semiconductor laser device has the same structure as the conventional broad-area type semiconductor laser device, except that both side regions of light emission areas of active and clad layers are two-dimensional-photonic-crystallized. The two-dimensional photonic crystal formed on both side regions of the light emission area is the crystal having the property that 780 nm laser light cannot be wave-guided in a resonator direction parallel to a striped ridge within the region. The light traveling in the direction can exist only in the light emission area sandwiched between two photonic crystal regions, which results in the light laterally confined by the photonic crystal region. The optical confinement of the region suppresses the loss in the light at both edges of the stripe serving as the boundary of the optical confinement, which reduces the curve of wave surface and uniforms the light intensity distributions of NFP and FFP.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] The present document is based on Japanese Priority DocumentJP2002-338782, filed in the Japanese Patent Office on Nov. 22, 2002, theentire contents of which being incorporated herein by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a semiconductor laser device anda method of manufacturing the same, and relates more particularly to abroad-area type semiconductor laser device in which light intensitydistributions of a near field pattern (hereafter, referred to as NFP)and a far field pattern (hereafter, referred to as FFP) are uniform, andto a method of manufacturing such a semiconductor laser device.

[0004] 2. Description of Related Art

[0005] The broad-area type semiconductor laser device in which a stripewidth is larger than 10 μm is frequently used for a light source of alaser printer or a display apparatus, as a high output typesemiconductor laser device.

[0006] Here, the configuration of a conventional AlGaAs-based broad-areatype semiconductor laser device is described with reference to FIG. 5.FIG. 5 is a sectional view showing the configuration of the AlGaAs-basedbroad-area type semiconductor laser device. A conventional AlGaAs-basedbroad-area type semiconductor laser device 10 (hereafter, referred to asa conventional semiconductor laser device 10) is the semiconductor laserdevice for oscillating a laser light whose wavelength is 780 nm. Asshown in FIG. 5, this has the multilayer structure composed of ann-Al_(0.7)Ga_(0.3)As clad layer 14, an n-Al_(0.3)Ga_(0.7)As guide layer16, an Al_(0.1)Ga_(0.9)As active layer 18, a p-Al_(0.3)Ga_(0.7)As guidelayer 20, a p-Al_(0.7)Ga_(0.3)As clad layer 22 and a p-GaAs cap layer24, which are grown sequentially on an n⁺-GaAs substrate 12.

[0007] In the multilayer structure, the upper layers of the p-GaAs caplayer 24 and the p-AlGaAs clad layer 22 are processed as striped ridges,and n-GaAs current block layers 26 are embedded on both sides of theridges. A p-side electrode 28 is formed on the p-GaAs cap layer 24 andthe n-GaAs current block layer 26, and an n-side electrode 30 is formedon the rear surface of the n⁺-GaAs substrate 12.

[0008] When the above-mentioned conventional semiconductor laser deviceis manufactured, the n-Al_(0.7)Ga_(0.3)As clad layer 14, then-Al_(0.3)Ga_(0.7)As guide layer 16, the Al_(0.1)Ga_(0.9)As active layer18, the p-Al_(0.3)Ga_(0.7)As guide layer 20, the p-Al_(0.7)Ga_(0.3)Asclad layer 22 and the p-GaAs cap layer 24 are epitaxially grownsequentially on the n⁺-GaAs substrate 12 by using a metal organicchemical vapor deposition method (MOCVD method) and the like.Consequently, the multilayer structure is formed. Next, in themultilayer structure, the upper layers of the p-GaAs cap layer 24 andthe p-AlGaAs clad layer 22 are etched to thereby form the stripedridges. Subsequently, the n-GaAs current block layers 26 are embeddedand grown on both sides of the ridges, and the ridges are embedded.Next, the p-side electrode 28 is formed on the p-GaAs cap layer 24 andthe n-GaAs current block layer 26, and the rear surface of the n⁺-GaAssubstrate 12 is polished to thereby adjust the thickness of thesubstrate. After that, the n-side electrode 30 is formed on the rearsurface (for example, refer to a non-patent document 1).

[0009] The lateral mode of the laser light emitted from thesemiconductor laser device has a large influence on the suitability ofthe device property of the semiconductor laser device when thesemiconductor laser device is applied as the light source. In short, thelateral mode control to stably control the light mode in the lateraldirection of the laser light emitted from the semiconductor laser deviceto a basic (0-th) mode is one of the important points for the control ofthe semiconductor laser device. In particular, the broad-area typesemiconductor laser device as mentioned above has the wide stripe width.Thus, the lateral mode is apt to be a multi mode. Hence, it is difficultthat the light intensity distributions of the NFP and the FFP becomeuniform. If the semiconductor laser device, in which the light intensitydistributions of the NFP and the FFP are not uniform, is used as thelight sources for printing and the like, the irregularity in the lightintensity is brought about to thereby bring about the irregularity inprinted characters. Also, if this is applied to a display, the imagequality of a displayed image is deteriorated.

[0010] [Non-Patent Document 1]

[0011] “Basics and Application of Understandable Semiconductor LaserDevice” Written by Shoji Hirata, Edited by Ohmsha Ltd. in 2001, pages180 to 182.

SUMMARY OF THE INVENTION

[0012] Accordingly, there has been a need to provide a semiconductorlaser device in which the light intensity distributions of NFP and FFPare uniform, and a method of manufacturing the same.

[0013] By the way, the irregularities in the intensities of the NFP andthe FFP are thought to be caused by the fact that a wave-guide surfaceis curved, in addition to the fact that the lateral mode is a multi-modevibration. That is, the fact that the curve of the wave-guide surfacecauses the light intensity to tend to be concentrated on edges of bothsides of the stripe is thought to be one factor of the occurrence of theirregularities in the intensities of the NFP and the FFP. And, one ofthe causes of the curved wave-guide surface results from the delay inthe travel of the wave-guidance because the loss of the light occurs atthe edges of both sides of the stripe.

[0014] So, the present inventors thought up the idea of suppressing theloss of the light at both side edges of the stripe and suppressing thecurve of the wave-guide surface and thereby uniforming the lightintensity distributions of the NFP and the FFP on the wave-guide surfacein the semiconductor laser device. Moreover, in the course of continuingwith the research to solve the above-mentioned problems, the presentinventors thought up the idea ofmulti-dimensional-photonic-crystallizing, for example,two-dimensional-photonic-crystallizing the regions on both sides of thelight emission area or on the light emission area. This is because thetwo-dimensional photonic crystallization enables the formation of thestructure in which the light having a particular wavelength traveling ina particular direction cannot exist, and enables the control of thewave-guide situation to the particular direction of the light having theparticular wavelength. The multi-dimensional-photonic-crystal, forexample, the two-dimensional photonic crystal, depending on thestructure design, disables the existence of the light having theparticular wavelength traveling in the particular direction, or enablesthe promotion of the wave-guidance in the particular direction of thelight having the particular wavelength, whereby the wave-guide situationcan be controlled.

[0015] Then, the present inventors discovered the fact that byintroducing the two- or multi-dimensional photonic crystal region intoany of the active layer, the guide layer and the clad layer in thesemiconductor laser device, and then defining the light emission area onthe basis of the photonic crystal region, and thereby controlling thetraveling manner of the light wave-guided through the light emissionarea on the basis of the photonic crystal region, it is possible touniform the light intensity distributions of the NFP and the FFP in thesemiconductor laser device, and thereby possible to control the lateralmode.

[0016] The photonic crystal implies “artificial multi-dimensionalperiodic structure having periodic property of level similar towavelength of light”, for example, as introduced on a page 1524 of “0plus E” magazine in December 1999. It should be noted that “this doesnot indicate so-called optical crystal material”. The above-mentionedperiodicity implies the periodicity with regard to the distribution ofrefractive indexes, in many cases. An example of the photonic crystal isalso reported in the same magazine. The photonic crystals in which theperiodicities of the refractive index distributions are atwo-dimensional direction and a third-dimensional direction are referredto as a two-dimensional photonic crystal and a third-dimensionalphotonic crystal, respectively.

[0017] In other words, the photonic crystal is the structure in whichunits have different refractive indexes, each of the units has a sizesimilar to a wavelength of a light, and the units are arrayed such thatrefractive indexes are periodically changed in one-dimension ormulti-dimensional area. This is expected as the material that enables anoptical device having an excellent optical property, which cannot beobtained from conventional optical materials, to be attained bydesigning the material and the structure depending on a purpose. Forexample, an optical wave-guide device, a polarization splitter, a doublerefraction device for a visible region, and the like, in which thephotonic crystal is used, are proposed.

[0018] In order to attain the above-mentioned purposes, from theabove-mentioned viewpoints, the semiconductor laser device according tothe present invention (hereafter, referred to as a first invention) is asemiconductor laser device having a multilayer structure including atleast an active layer, a guide layer and a clad layer, wherein regionson both sides of a light emission area in one of the active layer, theguide layer and the clad layer aremulti-dimensional-photonic-crystallized.

[0019] Preferably, the multi-dimensional-photonic-crystallized regionson both sides of the light emission area are in the active layer and inthe guide layer formed on the active layer, and further, themulti-dimensional-photonic-crystallized regions on both sides of thelight emission area are multi-dimensional-photonic-crystallized to astructure in which a laser light is not wave-guided in a resonatorlength direction. The multi-dimensional photonic crystallization iscarried out to thereby generate the particular region where the lightwave-guided in a resonator length direction cannot exist. Then, theparticular region is used to carry out an optical confinement. Thus, theloss of the light is suppressed at both edges of the stripe serving as aboundary of the confinement, namely, the boundary between the lightemission area and the particular region. The curve of a wave-guidesurface is reduced, and the light intensity distributions of the NFP andthe FFP are made uniform.

[0020] Another semiconductor laser device according to the presentinvention (hereafter, referred to as a second invention) is asemiconductor laser device having a multilayer structure including atleast an active layer, a guide layer and a clad layer, wherein a regionon a light emission area of the guide layer formed on the active layeror a region below a light emission area of the guide layer formed underthe active layer is multi-dimensional-photonic-crystallized.

[0021] Moreover, regions below both light emission areas of the guidelayer formed under the active layer and a compound semiconductor layerformed under the guide layer aremulti-dimensional-photonic-crystallized.

[0022] In the second invention, preferably, themulti-dimensional-photonic-crystallized region is formed such a way thatthe wave-guidance in the resonator length direction of the laser lightis promoted. The multi-dimensional-photonic-crystallized region has thecrystal structure having the property to promote the wave-guidance ofthe laser light in the resonator length direction. Thus, the laser lighttraveling in the resonator direction is affected by the photoniccrystallization region and stably wave-guided in the resonator lengthdirection.

[0023] In the multi-dimensional-photonic-crystallized region of theconcrete embodiments in the first and second inventions, micro poresextended in a direction vertical to a pn junction plane of the compoundsemiconductor layer constituting the multilayer structure are arrangedat a periodic array. The present invention can be applied without anyrestriction on the composition of the compound semiconductor layer ofthe multilayer structure constituting the semiconductor laser device andthe kind of the substrate. For example, it can be applied to thesemiconductor laser device of an AlGaAs-based, a GaN-based, an InP-basedand the like. In particular, it can be preferably applied to thebroad-area type semiconductor laser device in which the width of thelight emission area extended in the stripe shaped on the surfaceparallel to the pn junction plane of the compound semiconductor layerconstituting the multilayer structure is 10 μm or more. Also, it can bepreferably applied to a so-called edge-emitting semiconductor laserdevice in which a light output direction is not vertical to the pnjunction plane.

[0024] A method of manufacturing a semiconductor laser device accordingto the present invention (hereafter, referred to as a first inventionmethod) is a method of manufacturing a semiconductor laser device havinga multilayer structure including at least an active layer, a guide layerand a clad layer; including the steps of: growing a predeterminedcompound semiconductor layer, and forming the multilayer structurehaving the guide layer on the active layer; forming micro pores extendedin a multilayer direction of the multilayer structure so as to form aperiodic array, on both side regions of a light emission area of theguide layer, and carrying out amulti-dimensional-photonic-crystallization; and growing the clad layeron the guide layer that includes themulti-dimensional-photonic-crystallized region, and further forming apredetermined compound semiconductor layer thereon, to form themultilayer structure.

[0025] Another method of manufacturing a semiconductor laser deviceaccording to the present invention (hereafter, referred to as a secondinvention method) is a method of manufacturing a semiconductor laserdevice having a multilayer structure including at least an active layer,a guide layer and a clad layer; including the steps of: growing apredetermined compound semiconductor layer, and forming the multilayerstructure having the guide layer on the active layer; forming micropores extended in a multilayer direction of the multilayer structure soas to form periodic array, on a region of a light emission area of theguide layer, and carrying out amulti-dimensional-photonic-crystallization; and growing the clad layeron the guide layer that includes themulti-dimensional-photonic-crystallized region, and further forming apredetermined compound semiconductor layer, to form the multilayerstructure.

[0026] At the step of forming the micro pores extended in the multilayerdirection of the multilayer structure so as to form the periodic arrayand then carrying out the multi-dimensional-photonic-crystallization,the typical photo lithography technique and etching processing techniqueare used to form the micro pores at the periodic array.

[0027] As mentioned above, according to the first invention, the regionson both sides of the light emission area in any layer of the activelayer, the guide layer and the clad layer aremulti-dimensional-photonic-crystallized, for example,two-dimensional-photonic-crystallized to thereby generate the particularregion, in which the light wave guided in the resonator length directioncan not exist, on both sides of the light emission area. Then, theparticular region is used to carry out the optical confinement.Consequently, the loss of the light at both edges of the stripe servingas the boundary of the optical confinement, namely, the boundary betweenthe light emission area and the particular region is suppressed, whichreduces the curve of the wave-guide surface and uniforms the lightintensity distributions of the NFP and the FFP.

[0028] According to the second invention, the region on the lightemission area or below the light emission area of the guide layer, andthe guide layer formed below the light emission area and the compoundsemiconductor layer formed under the guide layer aremulti-dimensional-photonic-crystallized, for example,two-dimensional-photonic-crystallized, which thereby enables themulti-dimensional-photonic-crystallized region to have the crystalstructure having the property to promote the wave-guidance of the laserlight in the resonator length direction. Moreover, the laser lighttraveling in the resonator length direction is affected by the photoniccrystallization region and stably wave-guided in the resonator lengthdirection. Hence, the semiconductor laser device can be attained inwhich the light intensity distributions of the NFP and the FFP areuniform.

[0029] The first and second invention methods are suitable for thebroad-area type semiconductor laser device in which the stripe width ofthe light emission area is 10 μm or more. Each of the fist and secondinvention methods attains the manufacturing method suitable for thesemiconductor laser device according to the first and second inventions.

BRIEF DESCRIPTION OF THE DRAWINGS

[0030]FIG. 1 is a sectional view showing a configuration of asemiconductor laser device of a first embodiment;

[0031]FIGS. 2A, 2B are sectional views at main steps when theabove-mentioned semiconductor laser device 40 is manufactured inaccordance with a method in the first embodiment;

[0032]FIG. 3 is a sectional view showing a configuration of asemiconductor laser device of a third embodiment;

[0033]FIGS. 4A, 4B are sectional views of the above-mentionedsemiconductor laser device 40 at main process steps when it ismanufactured in accordance with a method in a second embodiment; and

[0034]FIG. 5 is a sectional view showing a configuration of aconventional broad-area type semiconductor laser device.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035] Embodiments of the present invention will be described below inconcrete and in detail by exemplifying embodiments and referring to theattached drawings. By the way, a film forming method, a composition anda film thickness of a compound semiconductor layer, a ridge width, aprocessing condition and the like, which are described in the followingembodiments, are one exemplification to easily understand the presentinvention. Thus, the present invention is not limited to thisexemplification.

[0036] First Embodiment of Semiconductor Laser Device

[0037] This embodiment is one example of the semiconductor laser deviceaccording to the present invention. FIG. 1 is a sectional view showingthe configuration of the semiconductor laser device of this embodiment.In the members shown in FIG. 1, the same symbols are given to the samemembers as those in FIG. 5. A semiconductor laser device 40 in thisembodiment is the broad-area type semiconductor laser device whoseoscillation wavelength is 780 nm. As shown in FIG. 1, this has the sameconfiguration and the same layer structure as the conventionalbroad-area type semiconductor laser device 10, except that thetwo-dimensional photonic crystallization is performed on regions 44 onboth sides of a light emission area 42 of an AlGaAs active layer 18 anda p-AlGaAs guide layer 20. Here, the light emission area 42 is theregion immediately under a striped p-GaAs cap layer 24 surrounded by ann-GaAs current block layer 26.

[0038] The structure of the two-dimensional photonic crystal formed inthe regions 44 on both sides of the light emission area 42 is thestructure in which innumerable micro pores extended in the directionvertical to the substrate surface of an n⁺-GaAs substrate 12 arearranged in the regions 44 on both sides of the light emission area 42in a periodic array, as shown in FIG. 2B, and this is the crystalstructure having the property that the laser light of 780 nm can not bewave-guided in a direction (a direction of a resonator length, namely, adirection represented by an arrow in FIG. 2B) parallel to a stripedridge within the region 44. Thus, the light of 780 nm traveling in theresonator direction can exist only in the light emission area 42surrounded by the two photonic crystal regions 44. Hence, it becomes atthe situation of a lateral optical confinement caused by the photoniccrystal region 44.

[0039] In the semiconductor laser device 40 in this embodiment, asmentioned above, the two-dimensional photonic crystallization is carriedout to thereby generate the region 44 where the light wave-guided in theresonator length direction cannot exist, and the region 44 is used tocarry out the optical confinement. Thus, the loss of the light issuppressed at both edges of the stripe serving as the boundary of theoptical confinement, namely, the boundary between the region 42 and theregion 44. The curve of a wave-guide surface is reduced. Hence, thelight intensity distributions of the NFP and the FFP become uniform.

[0040] First Embodiment of Method of Manufacturing Semiconductor LaserDevice

[0041] This embodiment is one example in which the manufacturing methodof the semiconductor laser device according to the first inventionmethod is applied to the above-mentioned manufacturing of thesemiconductor laser device 40. FIGS. 2A, 2B are sectional views of theabove-mentioned semiconductor laser device 40 at the main process stepswhen it is manufactured in accordance with the method in thisembodiment. In the members shown in FIGS. 2A, 2B, the same symbols aregiven to the same members as those in FIG. 5. In accordance with themethod of this embodiment, when the above-mentioned semiconductor laserdevice 40 is manufactured, at first, the n-Al_(0.7)Ga_(0.3)As clad layer14, the n-Al_(0.3)Ga_(0.7)As guide layer 16, the Al_(0.1)Ga_(0.9)Asactive layer 18 and the p-Al_(0.3)Ga_(0.7)As guide layer 20 areepitaxially grown sequentially on the n⁺-GaAs substrate 12 by using themetal organic chemical vapor deposition method (MOCVD method) and thelike, as shown in FIG. 2A, similarly to the conventional method, wherebythe multilayer structure is formed.

[0042] After the formation of the multilayer structure, a wafer is takenout of a crystal growing apparatus. Subsequently, a mask (not shown)that has the pattern in which micro pores are arrayed at a periodicarray on the region 44 where the photonic crystallization is performed,namely, the stripe-shaped region 44 on both sides of the light emissionarea 42 and perfectly covers the regions except the regions 44 includingthe light emission area 42 is formed on the p-AlGaAs guide layer 20. Forexample, photo-resist, SiO₂ and the like are used for the mask material.Next, a proper etching method, such as an RIE (Reactive Ion Etching)method and the like, is used to etch the AlGaAs active layer 18 and thep-AlGaAs guide layer 20. When the mask is removed after the etching, themicro pores 46 are formed at the same periodic array as the periodicarray of the micro pores formed on the mask, on the region 44 in thep-AlGaAs guide layer 20 and in the AlGaAs active layer 18, as shown inFIG. 2B. Consequently, the two-dimensional photonic crystallization isattained. The depth in the photonic crystallization can be adjusted byadjusting the etching condition and thereby controlling the depth of thevacancies 26.

[0043] Next, the wafer is again set in the crystal growing apparatus.Then, the p-Al_(0.7)Ga_(0.3)As clad layer 22 and the p-GaAs cap layer 24are epitaxially grown to thereby form the multilayer structure.Subsequently, similarly to the conventional method, the ridge is formedand embedded, and the p-side electrode 28 and the n-side electrode 30are formed.

[0044] Second Embodiment of Semiconductor Laser Device

[0045] This embodiment is another example of the semiconductor laserdevice according to the first invention. In the first embodiment, theregion 44 is photonic-crystallized and has the structure of thetwo-dimensional photonic crystal. However, in this embodiment, theregion 44 is three-dimensional-photonic-crystallized by a microprocessing technique. In the three-dimensional photonic crystal, theproper design of the photonic crystal structure enables the attainmentof the condition at which the light having a particular wavelength isnever propagated independently of a direction, namely, the light havingthe particular wavelength can not exist at all. So, the introduction ofthe three-dimensional photonic crystal structure into the regions 44enables the regions 44 on both sides of the light emission area 42 to bethe region where the laser light cannot exist at all. Thus, in thisembodiment, the loss of the light at both edges of the stripe is furthersuppressed over the first embodiment introducing the two-dimensionalphotonic crystal, and the curve of a wave-guide surface is reduced tothereby uniform the light intensity distributions of the NFP and theFFP.

[0046] Third Embodiment of the Semiconductor Laser Device

[0047] This embodiment is one example of the semiconductor laser deviceaccording to the second invention. FIG. 3 is a sectional view showingthe configuration of the semiconductor laser device of this embodiment.In the members shown in FIG. 3, the same symbols are given to the samemembers as those in FIG. 5. A semiconductor laser device 50 in thisembodiment is a broad-area type semiconductor laser device whoseoscillation wavelength is 780 nm. As shown in FIG. 3, this has the sameconfiguration and the same layer structure as the conventionalbroad-area type semiconductor laser device 10, except that the a region54 of the p-AlGaAs guide layer 20 on a light emission area 52 istwo-dimensional-photonic-crystallized.

[0048] The structure of the two-dimensional photonic crystal formed onthe region 54 of the p-AlGaAs guide layer 20 is the structure in whichthe innumerable micro pores extended in the direction vertical to thesubstrate surface of the n⁺-GaAs substrate 12 are arranged in theregions 54 on the light emission area 52 in a periodic array, as shownin FIG. 4B, and this is the crystal structure having the property thatthe laser light of 780 nm promotes the wave guidance in a direction (adirection of a resonator length, namely, a direction represented by anarrow in FIG. 4B) parallel to the striped ridge. In other words, thestructure of the two-dimensional photonic crystal shown in FIG. 2B isthe structure to promote the light, in which the oscillation wavelengthof the laser is, for example, 780 nm, to be wave-guided in the arrowdirection (the direction of the resonator) in FIG. 4B. Thus, it isdifficult that the light in the direction different from the arrowdirection is wave-guided.

[0049] Consequently, the light of 780 nm traveling in the resonatordirection is affected by the photonic crystallized region 44 and stablywave-guided in the resonator length direction (the arrow direction inFIG. 4B). Also, the vacancies constituting the photonic crystalstructure are uniformly formed throughout the region 54 at the equalinterval. Thus, the influence of the wave-guidance also promoted by theregion 54 has the uniform influence on the entire area within the stripe(the light emission area). Hence, the light is wave-guided at theuniform intensity within the stripe. In this way, the region where thewave-guidance in the particular direction of the light having theparticular wavelength is promoted is used to carry out the opticalconfinement, which can attain the stabilization and the uniformity ofthe intensities of the wave-guided lights and can also uniform the lightintensity distributions of the NFP and the FFP.

[0050] Second Embodiment of Method of Manufacturing Semiconductor LaserDevice

[0051] This embodiment is one example in which the manufacturing methodof the semiconductor laser device according to the second inventionmethod is applied to the above-mentioned manufacturing of thesemiconductor laser device 50. FIGS. 4A, 4B are respective sectionalviews of the above-mentioned semiconductor laser device 50 at the mainprocess steps when it is manufactured in accordance with the method inthis embodiment. In the members shown in FIGS. 4A, 4B, the same symbolsare given to the same members as those in FIG. 5. In accordance with themethod of this embodiment, when the above-mentioned semiconductor laserdevice 50 is manufactured, at first, the n-Al_(0.7)Ga_(0.3)As clad layer14, the n-Al_(0.3)Ga_(0.7)As guide layer 16, the Al_(0.1)Ga_(0.9)Asactive layer 18 and the p-Al_(0.3)Ga_(0.7)As guide layer 20 areepitaxially grown sequentially on the n⁺-GaAs substrate 12 by using themetal organic chemical vapor deposition method (MOCVD method) and thelike, similarly to the conventional method, whereby the multilayerstructure is formed.

[0052] After the formation of the multilayer structure, the wafer istaken out of the crystal growing apparatus. Subsequently, on the region54 where the photonic crystallization is performed, namely, the region54 on the light emission area 52 of the p-AlGaAs guide layer 20, a mask(not shown) that has the pattern in which the micro pores are arrayed atthe periodic array and perfectly covers the regions except the region 54is formed on the p-AlGaAs guide layer 20. For example, the photo-resist,the SiO₂ and the like are used for the mask material. Next, the properetching method, such as the RIE (Reactive Ion Etching) method and thelike, is used to etch the p-AlGaAs guide layer 20. When the mask isremoved after the etching, the micro pores 56 are formed at the sameperiodic array as the periodic array of the micro pores formed on themask, on the region 54 of the p-AlGaAs guide layer 20, as shown in FIG.4B. Consequently, the two-dimensional photonic crystallization isattained. The depth in the photonic crystallization can be adjusted byadjusting the etching condition and thereby controlling the depth of thevacancies 56.

[0053] Next, the wafer is again set in the crystal growing apparatus.Then, the p-Al_(0.7)Ga_(0.3)As clad layer 22 and the p-GaAs cap layer 24are epitaxially grown to thereby form the multilayer structure.Subsequently, similarly to the conventional method, a ridge is formedand embedded, and the p-side electrode 28 and the n-side electrode 30are formed.

[0054] In this embodiment, the region 54 on the light emission area 52is photonic-crystallized. A width of the region 54 on which the photoniccrystallization is performed does not need to be perfectly coincidentwith a width of the light emission area 52. It may be the region 54having a width slightly larger than that of the light emission area 52.Also, in this embodiment, it is necessary to define a thickness in sucha way that a thickness of the layer on which the photoniccrystallization is performed is a thickness in a range in which theactive layer 18 is not damaged and that the light wave-guided throughthe active layer 18 receives the influence of the photoniccrystallization region.

[0055] Fourth Embodiment of Semiconductor Laser Device

[0056] This embodiment is still another example of the semiconductorlaser device according to the second invention. In the third embodiment,the region 54 of the p-AlGaAs guide layer 20 is photonic-crystallized sothat it has the structure of the two-dimensional photonic crystal.However, in this embodiment, although not shown, the region below thelight emission area 52 of the n-AlGaAs guide layer 16 and the region ofthe n-AlGaAs clad layer 14 under it aretwo-dimensional-photonic-crystallized. Thus, it is possible to providethe same effect as the third embodiment. When the semiconductor laserdevice in this embodiment is manufactured, after the formation of then-AlGaAs guide layer 16, the predetermined region isphotonic-crystallized similarly to the manufacturing method of thesemiconductor laser device in the second embodiment. Subsequently,similarly to the conventional method, the layers on and after the AlGaAsactive layer 18 is epitaxially grown to thereby form the multilayerstructure. Then, the ridge is formed, and the semiconductor laser deviceis manufactured.

[0057] In the first to fourth embodiments of the semiconductor laserdevice and the first and second embodiments of the manufacturing methodof the semiconductor laser device, they have been explained byexemplifying the AlGaAs-based semiconductor laser device. However, thepresent invention is not limited to the AlGaAs-based semiconductor laserdevice. Naturally, it can be applied to even a semiconductor laserdevice of a GaN-based, an InP-based and the like.

[0058] Finally, the embodiments and examples described above are onlyexamples of the present invention. It should be noted that the presentinvention is not restricted only to such embodiments and examples, andvarious modifications, combinations and sub-combinations in accordancewith its design or the like may be made without departing from the scopeof the present invention.

What is claimed is:
 1. A semiconductor laser device comprising amultilayer structure including at least an active layer, a guide layerand a clad layer, wherein regions on both sides of a light emission areain one of said active layer, said guide layer and said clad layer ismulti-dimensional-photonic-crystallized.
 2. The semiconductor laserdevice according to claim 1, wherein saidmulti-dimensional-photonic-crystallized regions on both sides of saidlight emission area are in active layer and in said guide layer formedon said active layer.
 3. The semiconductor laser device according toclaim 1 or 2, wherein said multi-dimensional-photonic-crystallizedregions on both sides of said light emission area are formed in such away that a laser light is not wave-guided in a resonator lengthdirection.
 4. A semiconductor laser device comprising a multilayerstructure including at least an active layer, a guide layer and a cladlayer, wherein a region above a light emission area of said guide layerformed on said active layer or a region below a light emission area ofsaid guide layer formed under said active layer ismulti-dimensional-photonic-crystallized.
 5. A semiconductor laser devicecomprising a multilayer structure including at least an active layer, aguide layer and a clad layer, wherein regions below both light emissionareas of said guide layer formed under said active layer and a compoundsemiconductor layer formed under said guide layer aremulti-dimensional-photonic-crystallized.
 6. The semiconductor laserdevice according to claim 4 or 5, wherein saidmulti-dimensional-photonic-crystallized region of said guide layer isformed in such a way that a wave-guidance in a resonator lengthdirection of a laser light is promoted.
 7. The semiconductor laserdevice according to claims 1, 4, or 5, wherein a width of a lightemission area extended in a stripe shaped on a surface parallel to a pnjunction plane of said compound semiconductor layer constituting saidmultilayer structure is 10 μm or more.
 8. The semiconductor laser deviceaccording to claims 1, 4, or 5, wherein a width of a light emission areaextended in a stripe shaped on a surface parallel to a pn junction planeof said compound semiconductor layer constituting said multilayerstructure is 10 μm or more, and a direction in which the light isemitted is not vertical to said pn junction plane.
 9. The semiconductorlaser device according to claims 1, 4 or 5, wherein in saidmulti-dimensional-photonic-crystallized region, micro pores extended ina direction vertical to said pn junction plane of said compoundsemiconductor layer constituting said multilayer structure are arrangedat a periodic array.
 10. A method of manufacturing a semiconductor laserdevice comprising a multilayer structure including at least an activelayer, a guide layer and a clad layer; comprising the steps of: growinga predetermined compound semiconductor layer, and forming saidmultilayer structure having said guide layer on said active layer;forming micro pores extended in a layer direction of said multilayerstructure so as to form a periodic array, on both side regions of alight emission area of said guide layer, and carrying out amulti-dimensional-photonic-crystallization; and growing said clad layeron said guide layer that includes saidmulti-dimensional-photonic-crystallized region, and further forming apredetermined compound semiconductor layer thereon, to form saidmultilayer structure.
 11. A method of manufacturing a semiconductorlaser device comprising a multilayer structure including at least anactive layer, a guide layer and a clad layer; comprising the steps of:growing a predetermined compound semiconductor layer, and forming saidmultilayer structure having said guide layer on said active layer;forming micro pores extended in a layer direction of said multilayerstructure so as to form a periodic array, on a region of a lightemission area of said guide layer, and carrying out amulti-dimensional-photonic-crystallization; and growing said clad layeron said guide layer that includes saidmulti-dimensional-photonic-crystallized region, and further forming apredetermined compound semiconductor layer thereon, to form saidmultilayer structure.